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diff --git a/contrib/bind/doc/misc/rfc2317-notes.txt b/contrib/bind/doc/misc/rfc2317-notes.txt new file mode 100644 index 0000000..0b62d2a --- /dev/null +++ b/contrib/bind/doc/misc/rfc2317-notes.txt @@ -0,0 +1,105 @@ +Message-Id: <200005230246.WAA03750@hrothgar.gw.com> +To: ... +Subject: Notes on RFC-2317 +Date: Mon, 22 May 2000 22:46:55 -0400 +From: Kimmo Suominen <kim@tac.nyc.ny.us> + +Hi! + +I wrote down some notes on RFC-2317. I've had discussions with all of +you regarding classless IN-ADDR.ARPA delegations, and I would very much +appreciate any comments you may have. Please feel free to forward this +to other parties as you see necessary or appropriate. + +The goal of these notes is to try and clarify the reasoning behind the +recommendations I've been making on implementing RFC-2317 delegations. +In particular the following issues keep coming up with again and again +with each vendor: + + - why use "-" instead of "/" + - why use particular NS records + - why delegate within IN-ADDR.ARPA + +I am hoping that the these notes could eventually be used to convince +ISPs to provide an efficient and smooth implementation of RFC-2317 with +the least amount of headache for the end-user. + +Regards, ++ Kim + + + +NOTES ON IMPLEMENTING CLASSLESS IN-ADDR.ARPA DELEGATION PER RFC-2317 + +1. Selecting the CNAME target zone + + RFC-2317 shows an example case where the target zone is a delegated + sub-zone of the IN-ADDR.ARPA zone for the natural class C network. + This will allow for the NS records for the zone can be independently + selected (see benefits described below). An example of such a zone + would be 0-28.150.80.204.IN-ADDR.ARPA. + + Now pay careful attention to the last paragraph of RFC-2317. There + are broken resolver implementations that apply the "valid host name" + restrictions on the CNAME target (it should only be applied to the + PTR target name). To avoid problems with such implementations it + is best to use a character that is allowed in a hostname. I prefer + using a hyphen, as I did in the example above. + + Some ISPs may at first refuse to delegate these zones (without any + explanation). Approach such ISPs with the reasoning in here first, + but if that fails consider using your "forward" zone as a fallback. + + There is nothing magic about the IN-ADDR.ARPA zone for RFC-2317 + delegations. You will have to sacrifice the optimization provided + by a correct IN-ADDR.ARPA delegation, but you will still retain + the ease of local administration for all name changes. + + I recommend using a dedicated subdomain for the PTR records, e.g. if + your "forward" domain is "HOME.GW.COM" use "REV.HOME.GW.COM" for the + PTR records. + +2. Selecting the NS records + + The NS records for the delegated zone should include all the NS + records of the parent zone, in addition to any NS records pointing + to the public name servers the delegate may want to use. Having the + name servers of the parent zone secondary the delegated zone allows + them to have the necessary authoritative data to return the CNAME + target in the additional records of a response to a PTR record query + (minimizing the number of queries needed to resolve an address). + + This can be achieved using any zone (i.e. even a subdomain of your + "forward" domain), of course. However, having the ISP delegate an + IN-ADDR.ARPA zone for your PTR records rather than you delegating a + zone to your ISP maintains the logical "owner" and "delegate" roles. + + If the primary server for the delegated zone is not permanently on + the Internet (e.g. a dial-on-demand connection) then you would not + want to advertise it in the NS records. It would just be a stealth + server which the advertised secondaries poll for updates. + +3. Example delegation + + To delegate our example zone 0-28.150.80.204.IN-ADDR.ARPA first look + at the NS records of the parent zone 150.80.204.IN-ADDR.ARPA. Let's + say they are the following: + + $ORIGIN 150.80.204.IN-ADDR.ARPA. + @ IN NS GRENDEL.GW.COM. + IN NS PYRY.GW.COM. + + To delegate 204.80.150.0/28 to SRV.HOME.GW.COM you would then insert + these records in the parent zone data: + + $ORIGIN 150.80.204.IN-ADDR.ARPA. + 0-28 IN NS SRV.HOME.GW.COM. + IN NS GRENDEL.GW.COM. + IN NS PYRY.GW.COM. + $GENERATE 0-15 $ IN CNAME $.0-28.150.80.204.IN-ADDR.ARPA. + + The necessary modifications to /etc/named.conf will be left as an + exercise to the reader. + +Kimmo Suominen +Global Wire Oy |
